IMPROVEMENT OF KHORJINI CONNECTIONS

The purposeof this researchis tostudy the behaviorof conventional and retrofittedKhorjini connections. Four plates, which were welded between the beams and column, added to the common details of the connection. Two, common and retrofitted, connections were tested under monotonic loading. The tested specimens were modeled by a finite element method, which verified with experimental results. Several models with different size of the connection components were investigated using the verified FEM. The results indicated that a main defect of the conventional connections is severe stiffness deterioration, while Initial stiffness in the improved connections is more than four times the common detailed connections and stiffness deterioration is not a case of concern. Moreover, a great proportion of beam moment in Khorjini connections are carried to the column through beam flange to angle welds. Also, high stress concentration occurs in the elastic phase of the critical weld in a short length of the weld, which yields to stain jump, when the connection fails. However, in the retrofitted connections, added plates transfer a great amount of the connection moment to the column, which yields to a considerable reduction in the maximum plastic strains and von mises stresses in the critical weld. Consequently Retrofitted connections never fails, until beams reach to their ultimate plastic moments